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ALBUQUERQUE, N.M. — A rift widened between the U.S. Chamber of Commerce and some utilities as another major power provider quit over the business group's hard stance on pending climate regulation.

The Public Service Company of New Mexico, the state's largest utility, quit the chamber Friday just days after California's largest utility, Pacific Gas and Electric Co., said it was leaving because of the chamber's "extreme" positions.

Both sides of the climate change debate are escalating campaigns to sway national and global policy at a critical juncture.

It's among the hottest topics at the G-20 Summit in Pittsburgh, where President Obama indicated he would call for an end to government subsidies that encourage the use of fossil fuels, such as oil, coal and natural gas. Fossil fuels are blamed for contributing to global warming.

A major fight is expected when the climate bill heads to the Senate, perhaps by the end of the year, which is also when a pivotal U.N. climate conference takes place in Copenhagen.

At the heart of the ongoing clash with utilities is a statement from the Chamber of Commerce which asked that the science of global warming be put on "trial."

Many of the nation's largest utilities, along with the industry-backed Edison Electric Institute, favor legislation that would limits on carbon dioxide emissions. They have already committed billions to reduce emissions by buying energy from wind and solar farms, using nuclear power or trying to find ways to capture carbon dioxide emissions from power plants and store them underground.

"Not everybody agrees on everything but as the climate change debate has gone on, it has become clear to us that our position and the U.S. Chamber's position are not reconcilable," PNM spokesman Don Brown said Friday. "It doesn't make sense to us to be actively lobbying in D.C. for federal legislation at the same time that we're a member of an association that is aggressively opposing climate change legislation."

Other utilities say they disapprove of the chamber's position, they are staying put.

"We hope to convince other members why legislation to limit greenhouse gas emissions is critical," said Alex Schott, a spokesman for Entergy in New Orleans.

Chamber: Criticism is aimed at EPAChamber spokesman Eric Wohlschlegel said the chamber's message has become muddled and that it's not questioning the science behind climate change, but rather the science that the U.S. Environmental Protection Agency is using to regulate emissions.

"Our message has been if the EPA is going to actually promulgate a rule that is going to have this kind of cascading effect on the economy and jobs then they really need to be transparent and clear about the science," he said.

That argument didn't resonate with Pacific Gas and Electric Co. and other members.

The chamber spent $7.4 million lobbying on climate change and other issues in the quarter ended June 30, according to a disclosure report filed with July 20 with the House clerk's office.

PG&E said the chamber asked the company to reconsider its resignation, but spokesman Brian Hertzog said Friday that, "The chamber is on a different path."

Chairman and CEO Peter Darbee, in a resignation letter, cited the chamber's "extreme rhetoric and obstructionist tactics" over the climate change debate.

"We find it dismaying that the Chamber neglects the indisputable fact that a decisive majority of experts have said the data on global warming are compelling and point to a threat that cannot be ignored," Darbee wrote. "In our view, an intellectually honest argument over the best policy response to the challenges of climate change is one thing; disingenuous attempts to diminish or distort the reality of these challenges are quite another.

The chamber said the resignation of two members isn't too alarming, yet if the exodus continues the credibility of the organization could be threatened, especially if some of its biggest polluting members are leading the charge.

Utilities generate about 40 percent of the greenhouse gases in the U.S., which most power providers say is way too much.

World leaders gather in Thailand next week to discuss new curbs on greenhouse gas emissions and on Friday, the European Union urged all countries to bring more "urgency and ambition" to reach an agreement.

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